"Actually you are the first person to bring up this issue"

The bottom line here is not whether or not this issue is truthful, but how
and why it happens. I for one would like to know what the circumstances are
in each case that may trigger it.

As I've said previously, we ride a variety of singletrack and downhills
here, and the one time my QR let me down was traceable to my own fault.
After I tightened it up it didn't happen again the entire day. That was two
years ago and Blue Mountain. We had stopped off on the way back from
somewhere else and I happen to have the XC rig in the car. Everyone else was
riding FS freeride or DH bikes. I did the main ski run about 15 times that
afternoon...most of them "After" the QR came undone.

So the question is this: in each case where the problem occured, what were
the conditions? was it human error, or part failure?

"S o r n i" wrote:

Richard Bates wrote:
On Fri, 19 Mar 2004 11:37:22 -0500, in
, Sheldon Brown
wrote:

Sheldon "Insert Nickname Here" Brown

Is this a competition?

Umm, if it is you lose.

Don't pick "party doll"...

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

"Peter B" writes:

"Tim McNamara" wrote in message
...

See, that's the point. The brake should be designed so that it
*can't* force the wheel out of the dropouts, even if the QR is left
completely loose. It's a design flaw, an epic design flaw that
will cost some manufacturer a *lot* of money in court some day. No
other current brake design that I'm aware of puts an ejection force
into the wheel in normal operation, but front disk brakes do.

I'd have thought angling the drop-out so it faces forward would
prevent the axle rotating out if the pads are the pivot point. I'm
still trying to think of any negative implications from doing this
as it seems too easy.

Changing the dropout angle or created enclosed dropouts like
motorcycles use would be one solution.

Being cynical a non-mechanical implication would be manufacturers
seen to be fixing a problem they deny exists therefore admitting the
potential problem after the fact and leaving the industry wide open
to litigation.

Their lawyers may have told them exactly that. A much better
strategy- from the lawyers' perspective of course- is to sit back and
wait for the injury lawsuits to happen. Since this design flaw has
been publicly discussed and acknowledged by well-known engineers and
by trade industry magazines, there is already grounds for litigation
to be considered.

Simon Brooke wrote:

Merkins. They just don't do irony, do they? Something to do with only
having senses of humor, not of humour. There's a lot goes missing with
that second 'u'.

Not sure why you feel the need to resort to silly euro-trash snobbery for a
cheap joke. Check back on my original post and you'll see it had a good
amount of irony and sarcasm, all meant to find humor in the gyrations of the
obsessed, sorry you were too wrapped up in your own prejudices to get it.
Perhaps it was too sophisticated for your worn, tired, uk-centric world view
(see, it works both ways...) Thankfully most of your countrymen aren't
quite provincial. I would have goofed on anyone who posted similar tripe,
regardless of nationality.

The good Mr Annan can claim his knee-jerk defensiveness was an attempt at
humor, but I don't buy it. Taken in the context of his other posts, I'm not
sure why one is supposed to view that through a humo(u)rous lense while
taking him seriously in all the others. Taken at face value, he's just
plain full of ****. He rejects the notion of contacting an agency who can
*do* something about the perceived problems, then retorts that he tried and
failed. Methinks he may want to recheck his facts or re-evalute the
veracity of his opinion. Looks like the laugh's on you.

Tom

James Annan wrote:
tcmedara wrote:

LOL. While I think you are an obsessed quasi-religious zealot,
that's not why I'm going to goof on you.....

Dumabass, Frobnitz was *supporting you* !

Yeah, I realised that. I guess humo(u)r doesn't travel well.

Perhaps you should give it up for something you're better at...


He was suggesting that rather
than spam up a bunch of newsgroups where people are probably smart
enough to tighten their QR, you should direct your efforts at the
appropriate regulatory agencies and actually try to do something to
fix the "problem".

Actually, although you probably mean well, both you and Frobnitz don't
seem to realise that I _did_ contact the "appropriate regulatory
authorities" last year. They (or, to be precise, the CPSC) said they
needed specific complaints of individual problems, rather than a
general warning of a theoretical design problem.

I don't mean well at all. I responded 'cause I find humor in pointing out
logical inconsistency. I didn't "realise" you'd contact anyone because you
rejected the notion as not worthwhile. I'm pretty intelligent, but not
clairvoyent. I could have realized it had you bothered to mention it.
Maybe you should listen to the CPSC and ask why riders *haven't* contacted
said agency? Maybe your perception of the problem doesn't translate into
reality.

Of course, when I suggested that some of those riders who had
described their incidents might care to contact the CPSC, I was
roundly criticised for "scaremongering", and as far as I know, not a
single rider bothered. Many of those who understood the problem or
had even seen it for themselves had the touchingly naive belief that
the manufacturers would fix the problem all on their own and it would
be overkill to actually pressure them into doing so. Of course, what
they didn't realise is that the manufacturers have a strong financial
incentive to keep the current designs, since when Joe Bloggs upgrades
to disks and finds his QR fork is not up to the job, he then
generally goes out and buys a bolt-through fork. It's easy enough to
see who wins out of this.

Conspiricy theory itself is always touchingly naive. If the manufacturers
change the design then you're vindicated and if they don't, then they're
involved in the cover-up --and you're vindicated again! Is that how it
works in the land of absolute truth? (...and that's meant to be ironic
humor for your challenged countryman, Simon). Don't understand? Perhaps
you'd better start he http://tinyurl.com/282zg


Roll on one year, and entirely predictably, the manufacturers are
still pretending the problem doesn't exist. They must be laughing all
the way to the bank.

.....Or secure in the knowledge that the problem doesn't actually exist.

As for J DeMarco at the CPSC, well he commissioned Mark LaPlant of
Cannondale to report on the issue, and surprisingly enough the turkey
didn't vote for Christmas. In fact he produced a bull**** whitewash
which he refuses to publish. But since all the manufacturers can
(apparently truthfully) claim that no rider has ever reported any
incident, there really is little more that the CPSC can (or probably
should) do.

Again, not the "truth" you espouse so therefore it's a "whitewash". Next
you're going to tell us the CIA is behind it all right? Ya know, if you
could document actual circumstances (rather than internet anecdotes and
gossip), than you could prove the point to the apparently intransigent CPSC.

Your rejection of that course of action suggests that you're more
interested in pursuing your own personal crusade rather than
actually solving a problem -- percieved or otherwise.

Rather than thank him for the suggestion or offer a counterpoint to
why it's not a viable option,

I hope you will now agree that I have offered a counterpoint as to why
it is not a viable option, and I'm sorry for not giving sufficient
explanation earlier. The simple fact is that while MTBers refuse to do
more than grumble on bulletin boards, there is no real complaint to
raise with anyone. I realised several months ago that there was really
nothing more for me to do, but people still keep on emailing me with
their stories, and I thought this latest one was sufficiently
interesting to be worth sharing. Maybe next year there will be
another. Don't hold your breath.

So we can look forward to a year's peace on the matter? Or does this mean
that anytime someone reports a UFO, ....er disk/QR malfunction we'll be
treated to another lecture on the apathy of the injured and the evil intent
of the bike industry? You complain of apathy on the part of MTBers who do
nothing but "grumble on bulletin boards", and then resign yourself to do the
same. Again -- is this more of the internal debate going between the
personalities who live in your head? Maybe you nailed it by suggesting
"there is no complaint to raise with anyone."

Just a thought

Tom

Tim McNamara writes:

I keep hearing about this issue with greater frequency, but I've
been running discs for a few years now and it's only popped out
once in that time. It was my fault on that occasion, I realized
afterwards that I hadn't properly tightend the QR.

What means "properly tightened"?

See, that's the point. The brake should be designed so that it
*can't* force the wheel out of the dropouts, even if the QR is left
completely loose. It's a design flaw, an epic design flaw that will
cost some manufacturer a *lot* of money in court some day. No other
current brake design that I'm aware of puts an ejection force into
the wheel in normal operation, but front disk brakes do.

Hold it! Even though this has been discussed at great length here in
wreck.bike, it appears to me that most of the respondents did not
understand that a disc caliper behind the fork causes a wheel
disengaging force, and that repeated braking WILL loosen a QR.
Therefore, with the majority of contributors resting in the "James
Annan is all wrong" boat what you just posted gets us back to the
start, a few hundred responses ago.

Brake forces and their reactions are apparently to complex to be
discussed among bicyclists who believe anything bought in a bicycle
shop is safely designed.

http://www.ne.jp/asahi/julesandjames...quick_release/

Jobst Brandt

anonymous snipes:

The bottom line here is not whether or not this issue is truthful,
but how and why it happens. I for one would like to know what the
circumstances are in each case that may trigger it.

So the question is this: in each case where the problem occured,
what were the conditions? was it human error, or part failure?

How about doing a test that takes about 30 seconds. Open the QR on a
disc brake equipped front wheel. Push the bicycle forward and notice
what the axle does.

Just so it is clear what occurs. The fork dropout rises from the axle
and is retained only by the retention lips. the motion involved will
cause a properly closed QR to loosen on repeated hard braking because
there is ever so little motion with each brake application. If the QR
is extremely tight, it can prevent this over a longer time but in the
long run, if the wheel is not removed for one reason or another and
reinstalled again made extra tight, it will loosen.

The point is that the wheel should not have disengaging forces while
braking. These would not occur if the caliper were mounted in front
of the fork.

Jobst Brandt

wrote:
Tim McNamara writes:


Brake forces and their reactions are apparently to complex to be
discussed among bicyclists who believe anything bought in a bicycle
shop is safely designed.

http://www.ne.jp/asahi/julesandjames...quick_release/


I don't think that at all, but I'm also not going to condemn a product or
indict an entire industry as a result of some line drawings and vector
calculations. Apart from some internet anecdotes and urban legend, I've yet
to see anything remotely resembling evidence of a threat to the public
safety. To illustrate, my lovely wife subscribes to the CPSC mailing list.
We receive an email nearly ever day listing between 1 and 5 different
product recalls. These recalls typically describe what is often potential
flaws and possible dangers -- many of which are damn near laughable but
still result in a recall:

Here's a few examples:
http://tinyurl.com/223qd
http://tinyurl.com/2n2sn

Surf the site and ask yourself if the CPSC is going to overlook the disk
brake risk when bicycle product recalls are issued for injuries no more
severe than a broken finger. http://tinyurl.com/3yxvb

I'm the last person to believe the government (US or anywhere else) ought to
be the ever protective nanny, and I'm not suggesting that if the CPSC isn't
interested than there's no problem. I'm merely illustrating that the idea
of a huge conspiricy to cover up the problems, and a tremendous lack of hard
evidence suggests the "problem" exists in the realm of the theoretical only.

Hell, I don't even ride with disks and I think the whole debate is a crock.

Tom

"tcmedara" wrote in message
news:fx07c.17600$Cf3.3839@lakeread01...

I'm the last person to believe the government (US or anywhere else) ought
to
be the ever protective nanny, and I'm not suggesting that if the CPSC
isn't
interested than there's no problem. I'm merely illustrating that the idea
of a huge conspiricy to cover up the problems, and a tremendous lack of
hard
evidence suggests the "problem" exists in the realm of the theoretical
only.


It's not a conspiracy, it's a "we'll ignore this and hope it goes away".
It's not going to go away. I worked at a fork manufacturer who had two
major recalls. How long do you think it took them to admit there was a
problem? How long after that do you think it took the CPSC to get involved?
It wasn't overnight.

Hell, I don't even ride with disks and I think the whole debate is a
crock.


It's not a crock. There's much evidence that discs loosen QRs, and it's
obvious that the forces of the brake try to eject the front wheel. When I
tighten something, I expect it to stay tight. But I'll be checking my QRs
mid-ride these days, and someday I'll be buying a through-axle fork.

Greg

Tim McNamara writes:

I keep hearing about this issue with greater frequency, but I've
been running discs for a few years now and it's only popped out
once in that time. It was my fault on that occasion, I realized
afterwards that I hadn't properly tightend the QR.

What means "properly tightened"?

See, that's the point. The brake should be designed so that it
*can't* force the wheel out of the dropouts, even if the QR is left
completely loose. It's a design flaw, an epic design flaw that will
cost some manufacturer a *lot* of money in court some day. No other
current brake design that I'm aware of puts an ejection force into
the wheel in normal operation, but front disk brakes do.

Hold it! Even though this has been discussed at great length here in
wreck.bike, it appears to me that most of the respondents did not
understand that a disc caliper behind the fork causes a wheel
disengaging force, and that repeated braking WILL loosen a QR.
Therefore, with the majority of contributors resting in the "James
Annan is all wrong" boat what you just posted gets us back to the
start, a few hundred responses ago.

Brake forces and their reactions are apparently too complex to be
discussed among bicyclists who believe anything bought in a bicycle
shop is safely designed.

http://www.ne.jp/asahi/julesandjames...quick_release/

Jobst Brandt